This invention relates to a mixing valve for cold and hot water of the type including a thermostatic device and a manual control device acting upon the inlet ports that pass the cold and hot water to a mixing region.
According to Italian Patent No. 1,107,182 by the same inventor, a thermostatic faucet includes a mixer with manual control that sets a mixing ratio between cold water and hot water and a thermostatic device that, depending on the actual temperature of the mixed water, controls a choke valve inserted on the hot water supply to the manual control mixer so as to modify the mixing ratio set in order to maintain within a certain range the temperature of the mixed water that is actually delivered.
According to Italian Patent No. 1,279.194, by the same inventor, a thermostatic faucet includes a mixer with manual control that sets a mixing ratio between cold water and hot water and a thermostatic device that, depending on the actual temperature of the mixed water, controls a choke valve inserted on the cold water supply to the manual-control mixer so as to modify the mixing ratio set in order to maintain, within a certain range, the temperature of the mixed water that is actually delivered.
Both of these devices incorporate a certain material separation between the manually controlled mixer valve and the thermostatic device that complicates its design and installation.
According to Italian Patent No. 1,2273,178, a thermostatic mixing device to which one can also operate as a faucet includes inlet ports for cold water and hot water, arranged at the sides of a central outlet pipe. A mixing chamber receives water from regulated hot and cold inlet passages and a thermostatically controlled distribution valve operates so as to control the opening and closing in opposite directions of the respective regulated inlet hot and cold passages so as to maintain, within a certain and adjustable range, the temperature of the discharged mixed water. This device can be provided with a volume flow control valve for manually and simultaneously changing the useful opening of both hot and cold inlet pipes. The volume flow valve controls only the flow volume but does not have any effect on the mixing action or relative proportional of flow of hot and cold water. This device presents a general and particularly advantageous structure, although it does entail the inconvenience that temperature regulation is rather poorly sensitive and gives rise to a temporary over regulation phenomena (of referred to as an xe2x80x9covershootxe2x80x9d). Temporary overshoot occurs when upon movement of the temperature adjustment mechanism to a position corresponding to a given temperature, one initially gets an effective temperature change of discharged water that is considerably more than the desired change. The desired temperature change is reached only after a period of time after the thermostatic device had a chance to compensate. The adjustment of the temperature, controlled by the thermostatic element, is achieved by manual control of the position of the thermostatic element and the distribution valve operably connected to it, which directly affects the opening of the respective hot and cold inlets.
In accordance with one aspect of this invention, a thermostatic mixing valve can be used alternatively as a thermostatic faucet or as a thermostatic device for feeding one or several apparatus, each of which is provided with its own faucet, or with one or several faucets installed downstream from the thermostatic device. The thermostatic mixing valve combines the advantages of the prior art devices without entailing the installation or thermostatic overshoot inconveniences. In particular, the invention is a compact structure that is easy to make and install and ensures a high degree of adjustment sensitivity. It further can provide a guarantee against the delivery of excessively hot water also in the presence of abnormalities in water supply and, when it is used as a thermostatic faucet, it incorporates a manually operated sequential type control valve mounted in series with the thermostatic valve.
Preferably, the thermostatic mixing valve comprises two inlet ports for cold water and hot water, a mixing chamber, passages between the inlet ports and the mixing chamber, a discharge port from the mixing chamber for mixed water, a thermostatic element arranged at least partly in the mixing chamber, and an annular distribution slide valve controlled by the thermostatic element. Both inlet ports and discharge port are in a central body radially inside the annular distribution slide valve. The annular distribution slide valve is arranged so as to restrict the passage between only one of the inlet ports and the mixing chamber. A flow and mixing adjustment valve with manual control of the sequential type is mounted to control the two inlet ports.
The adjustment of the temperature of discharged water is set manually by the action of the manually operable sequential type control valve for the flow and the mixing action without the manual action directly changing the position of the thermostatic element and the distribution slide valve so that one can systematically eliminate the phenomenon of temporary overshoot. Furthermore, the action of adjusting the distribution slide valve, controlled by the thermostatic element, always works in a counteracting direction from the direction of manual action thereby limiting its effect. The consequence of two counteracting activities is that one must make a longer movement of the manual control to achieve a desired change. The gradation of adjustment is elongated and the profile of change is flatter. The quickness and precision of thermostatic adjustment are then enhanced by the fact that the distribution slide valve works so as to effectively restrict or increase flow cross section of only one of the inlet ports so that the mixing takes place due to the addition or restriction of only one flow to the volume of the other flow rather than through inverse variation of the volumes of the two flows.
In cases where the valve is used as a faucet, the manual operable sequential valve also intercepts or shuts off the delivered volume, functions as a non-return valve, and adjusts flow rate within certain limits. But the manual sequential valve inserted in the water supply lines can also be used as a thermostatic adjustment device for a water supply flow going to one or several apparatuses, each of which is provided with its own shut off and volume regulation valve or with one or several faucets inserted in the waterlines downstream from the thermostatic valves. In these cases, the manual control valve for the thermostatic valve is adjusted only to determine the desired temperature and not to intercept a shut-off water flow or regulate it.
In cases where one must ensure an upper limit of the temperature of the discharge water, the distribution slide valve is so positioned as to regulate, by the action of the thermostatic element, the cross-sectional area of the passage through which hot water passes from the pertinent inlet port to the mixing chamber.
On the other hand, in cases where it is not necessary to limit the temperature of the discharge water (for example, because hot water supply is provided at a limited or non-hazardous temperature), the distribution slide valve can also be arranged so as to regulate, by the action of the thermostatic element, the cross-sectional area of the passage through which cold water passes from the pertinent inlet port to the mixing chamber.
Preferably, when the valve is intended to be used a thermostatic faucet the manually operable sequential valve includes a pair of valve plates, preferably made of hard material with openings therethrough. A first fixed plate and a second moveable plate are in sliding contact with each other. The openings in the plates are positioned to ensure in succession a shut-off or intercept position, a range of sequential opening positions of the pertinent passage for cold water while retaining closure of passage for hot water, a range of positions for the sequential opening of a passage for hot water while retaining full opening of the passage for cold water and, finally a range of sequential closing of the passage for cold water while retaining full opening of the passage for the hot water. The two plates each present an outlet opening that is permanently open to the mixed flow.
As an alternative, the two ranges of positions can be replaced by a single range of positions in which there takes place a sequential opening of the passages for the hot water and simultaneously a sequential closing of the passages for the cold water.
The sequential action can be achieved, for example, with a plate valve structure that has a first plate that is symmetrical with respect to a diameter of the openings therethrough and with a second plate that is asymmetrically constructed with respect to a diameter of its openings, cooperating with the first plate openings. It is immaterial whether the first plate is fixed and the second plate is moveable or vice versa. In a particularly convenient arrangement, the sequential valve includes a fixed base plate intended to be mounted upon a supply and delivery housing, and a rotatable plate mounted rotatably on said base plate and which is manually operated. Preferably, the fixed base plate is mounted in the supply and delivery housing and the moveable part is mounted in a rotatable body of the valve and operable by a handle, lever, or knob.
The valve can be provided with an adjuster to determine and adjust the maximum temperature at which the delivered water can be adjusted. The adjuster adjusts the resting position of the thermostatic element and of the distribution slide valve connected to it. This device can include a cap that can be rotated by manual action, mounted through a working threaded connection to the rotatable body of the valve. As the cap is rotated relative to the rotatable body, the cap also axially shifts the support point to the thermostatic element.
In accordance with a broader aspect of the invention a thermostatic mixing valve has a base having two supply ports and a rotatable body mounted onto the base and operably connected to a first valving surface with a first and second inlet passages therethrough that are operably positioned adjacent the two supply ports for controlling volume flow into the housing. A second valving member is annular in shape and movable toward and away from an annular seat in proximity for restricting and controlling fluid only from said first inlet passage. The first inlet passage passes up through the annular seating surface within radial extent of said annular valving surface and having a downstream end in fluid communication with the annular seat and the annular valving member to provide a first annular flow path between the annular seat and the annular valving member from radially within the annular valving member to radially outside of the annular valving surface to a mixing chamber. The first inlet passage is sealed within the interior of said annular valving surface with respect to the second inlet passage from the supply ports to the mixing chamber. A thermostatic element is axially movably disposed within the mixing chamber and operably connected to the annular valving surface to move the annular valving surface axially toward and away from the annular seat for restricting controlling the flow form only the first inlet passage into the mixing chamber in response to the temperature of fluid in the mixing chamber. The mixing chamber is in fluid communication with an outlet exiting therefrom.
Preferably, the annular seat opposes an axial end of said annular valving member. The second inlet passage passes up through the first seating surface and through the interior of the annular valving surface within the radial extent of the annular valving surface and having a downstream end in unrestricted fluid communication with the mixing chamber.
Alternatively the second inlet passage ends below the annular valving member to allow free unrestricted flow about the annular valving member to the mixing chamber and the annular seat is positioned above the annular valving member and the first inlet passage passes up through the interior of the annular valving member.
Preferably, a return biasing spring is mounted within the radially confines of the annular valving member to axially move said annular valving member upon contraction of the thermostatic element.
In one embodiment the return biasing spring is mounted on the top of a central body within said rotatable body.